Wow! I sure got responces from you guys. For just a brief review. I have broken 10-12 intake rocker arms on my 51, 235. This is a car engine. It has hydralic lifters. The engine sat for 25 years in the truck before I got it. I got the truck thru a third party. The guy I got it from is dead now and the other two owners I don't know.I went thru the engine checking the bearings,compression and general condition. It turned out to be in pretty good shape and runs great. I had the head looked at by a guy who is also gone now. He pressure checked it, reseated the valves and milled the head just enough to clean and true the surface. How many times or how much it had been milled in the past I don't know. I pulled the head to check if the valve had hit the piston. There were no marks on either the piston or valve. I measured the cam lift and it came out to be as per Chevy specs. So, the lift isn't too high. If the head were milled too much the stock pushrods in effect could get too long since the rocker assembly would be closer to the block. The pushrod has a very big foot on it . I ground 1/8" off the foot and smoothed it out. After about 30 miles another rocker broke and one cracked. I'm pulling the head again to check the piston and valve. Does anyone know how you would check to see if the head is too short? There is no specific intake rocker that breaks. All but #1 has broken. If the height checks out I'll check the guides and valve height. If the head is too short I'll replace the engine. Also it just stopped oiling the rocker shaft so now I have to fix that. That is probably a crank shaft pull to get at the oil passages.
